Welcome Guest - Sign Up today
Welcome Guest - Sign Up today

Announcement

Collapse
No announcement yet.

Vortec Head Modification/Upgrade

Collapse
X
  • Filter
  • Time
  • Show
Clear All
new posts

  • #16
    Originally posted by FreeBeeTony View Post
    UPDATE:

    S question: can I simulate a 0.503" lift w/o the head installed and the cam creating the lift?
    Uuhhh press down on the valve stem .503"
    Cheesehead boating the Gulf Coast of FLA 27.51° N, 82.53° W

    1988 Cruisers Rogue 2420 -VP 290 DP now powered by custom 468 - https://forums.iboats.com/forum/owner...988-rogue-2420

    Past Boats
    1970 Wooster Hellion - Merc 9.8
    2002 SeaRay 190BR - 5.0 - A1G2 - "Cheeseheads in Paradise"
    1984 Avanti 170DLI -3.0 stringer- "Ship Happens"

    What’s behind you doesn’t matter.Enzo Ferrari

    Comment


    • #17
      Originally posted by Scott Danforth View Post

      Uuhhh press down on the valve stem .503"
      Lift the back end of the rocker 0.335" ???
      xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx
      The world takes on a whole new perspective when viewed from 100’ below.
      1972 Bertram ‘Bahia Mar’ 20
      2006 Mercruiser 4.3MPI (0W617679) w/Alpha One Gen II (0W829301)
      (Original - 1972 '165' In-line 6. Previous - 1994 4.3LX)


      Comment


      • #18
        Originally posted by Scott Danforth View Post

        Uuhhh press down on the valve stem .503"
        But how to do it in a controlled manner w/ simple tools?
        A big C-Clamp just came to mind.........
        '84 Grady White Offshore
        350 Mag w/ Vortec Heads
        Alpha 1 Drive

        Comment


        • #19
          I personally would use your drill press.

          however if your installed height for the correct springs is good, thats all that matters. the cam guys are smart enough to know which cam goes with which spring and what the installed height would need to be for clearance.
          Cheesehead boating the Gulf Coast of FLA 27.51° N, 82.53° W

          1988 Cruisers Rogue 2420 -VP 290 DP now powered by custom 468 - https://forums.iboats.com/forum/owner...988-rogue-2420

          Past Boats
          1970 Wooster Hellion - Merc 9.8
          2002 SeaRay 190BR - 5.0 - A1G2 - "Cheeseheads in Paradise"
          1984 Avanti 170DLI -3.0 stringer- "Ship Happens"

          What’s behind you doesn’t matter.Enzo Ferrari

          Comment


          • #20
            I did verify the installed height.
            I also checked for coil bind using a cut-off push rod and a C-Clamp.
            See pics below, adjusted for "zero-lash" and zero'd out my caliper, then adjusted the C-Clamp for ~0.35 lobe lift which would equate to 0.525 valve lift and took a pic of the spring.........looks like it still has more room so I'm pretty comfortable now.
            Next step will be to get under the cover and pull the heads off the engine,,,,,,hopefully before XMAS!

            '84 Grady White Offshore
            350 Mag w/ Vortec Heads
            Alpha 1 Drive

            Comment


            • #21
              Tony, just remember that total lift is the cam lobe lift AND the rocker arm ratio for total lift.
              NO PERSONAL QUESTIONS, THIS IS WHAT THE FORUM IS FOR.

              Comment


              • #22
                Originally posted by Bt Doctur View Post
                Tony, just remember that total lift is the cam lobe lift AND the rocker arm ratio for total lift.
                Understood, so when I increased the height of the back of the rocker arm by 0.35, the valve should have opened 0.525 (0.35*1.5); correct?
                Or am I missing something?
                '84 Grady White Offshore
                350 Mag w/ Vortec Heads
                Alpha 1 Drive

                Comment


                • #23
                  What's the lobe lift? Lift the back of the rocker by that amount. As the rocker is 1.5:1, the valve lift will be lobe lift * 1.5....

                  Chris......
                  xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx
                  The world takes on a whole new perspective when viewed from 100’ below.
                  1972 Bertram ‘Bahia Mar’ 20
                  2006 Mercruiser 4.3MPI (0W617679) w/Alpha One Gen II (0W829301)
                  (Original - 1972 '165' In-line 6. Previous - 1994 4.3LX)


                  Comment


                  • #24
                    Lobe lift from CompCam: 0.335.........so I used 0.35 in my test as in post #20.
                    '84 Grady White Offshore
                    350 Mag w/ Vortec Heads
                    Alpha 1 Drive

                    Comment


                    • #25
                      An observation, see pics below.
                      The valve stem on the exhaust valves protrude through the retainers more than the intake.
                      The rollers on the rockers just about make contact w/ the valve stem. Can I use different locks/keepers on the intake valves to make the retainers a bit lower?

                      '84 Grady White Offshore
                      350 Mag w/ Vortec Heads
                      Alpha 1 Drive

                      Comment


                      • #26
                        You will need to remove the valves and check their stem height first., from all my years in motors they should all be the same height. If the valves are exactly the same then the problem could be a seat installed too deep in the head.
                        NO PERSONAL QUESTIONS, THIS IS WHAT THE FORUM IS FOR.

                        Comment


                        • #27
                          I think it has more to do w/ the location of the keeper on the valve stem. Even if the valve was installed too deep or not deep enough it wouldn't change the amount the valve stem is sticking out past the retainer.
                          I am going to contact CompCams and ask their opinion. I had a similar problem when I had my heads redone by the machinist last time but it was much worse.
                          I have a feeling the dimension between the end of the valve stem and the location of the retainer-slot is different between the intake and the exhaust valves.
                          Will report back after I contact CompCams.

                          UPDATE:

                          Just found this !!!

                          Another difference between Vortec valves and the earlier non self aligning head valves is the tip length. Earlier valves are 0.250" on both intake and exhaust valves. Self aligning head intake valves have a 0.260" groove-to-tip length, exhaust valves use a 0.289" groove-to-tip length. That said, the typical SBC valve tip length of 0.250" will work just fine with self aligning rockers. Like with ANY rocker arm/valvetrain combination, the
                          valve train geometry
                          needs to be verified.
                          Last edited by FreeBeeTony; December 6th, 2018, 09:36 AM.
                          '84 Grady White Offshore
                          350 Mag w/ Vortec Heads
                          Alpha 1 Drive

                          Comment


                          • #28
                            MORE!!! Locks

                            Warning Note: On Vortec and other heads using self aligning rocker arms, using a +0.050" lock can cause interference between the rocker tip and the locks/retainer. Rocker contacting the locks/retainer has been encountered using a combination of c/n 906 Vortec heads, Comp Pro Magnum rockers p/n 1317, Comp retainer p/n 787, Comp spring p/n 26918, and the +0.050" locks.

                            The engine builder must mock up the assembly and check the clearance closely. In the case there's insufficient clearance, there are a few options:
                            • Use non self aligning rocker arms. Requires guide plates be installed.
                            • Use longer valves
                            • Use a different spring/retainer combo that uses a standard lock
                            • If just the locks are hitting the rocker, using a shorter (lash cap compatible) lock like the Edelbrock p/n 9615 may help. This 7 degree lock is 0.050" lower than a regular lock.
                            • Warning Use extreme caution if making the spring seat any deeper.

                            I contacted CompCams and their response was that they have not heard of the problem as I described.

                            I am going to continue to research and may elect to use different locks on the intake valves.

                            '84 Grady White Offshore
                            350 Mag w/ Vortec Heads
                            Alpha 1 Drive

                            Comment


                            • #29
                              Have the heads or block been milled? Pushrods may need to be custom fitted for length?

                              Comment


                              • #30
                                Sign up today
                                Think I may have found the answer to my dilemma............lash caps:

                                Includes 16 Hardened Lash Caps: 11/32 Stem Size, .210" Head Height, .080" Thickness These Hardened Valve Lash Caps have a .210" overall head height and .080" thickness. Because today's racing engines run at higher RPM levels with harsh cam profiles, the tip of the valve stem is subjected to a tremendous amount of pounding. These engines always run just on the brink of valve float – one of the most severe conditions that can exist. The best solution to this problem is the COMP Cams® Valve Lash Caps. These lash caps are precision machined and ground perfectly flat to maintain accuracy of valve train adjustment. A must have for titanium valves, these Lash Caps fit valve stems well and are easily removed.
                                '84 Grady White Offshore
                                350 Mag w/ Vortec Heads
                                Alpha 1 Drive

                                Comment

                                Working...
                                X